B-025 Validation of an open-channel assay for measuring serum angiotensin-converting enzyme (ACE) using the Cobas® Pro analyzer
Bibliographic record
Abstract
Abstract Background Angiotensin-converting enzyme (ACE) is a zinc-dependent carboxypeptidase that plays a central role in the renin-angiotensin-aldosterone system. It is primarily expressed in pulmonary capillaries and renal epithelial cells, with two catalytic domains (C-terminal and N-terminal) involved in blood pressure regulation. Serum ACE measurement is crucial for diagnosing and monitoring ACE-related conditions, including sarcoidosis and other granulomatous diseases. This study aimed to validate an open-channel assay for serum ACE on the cobas® c 503 analyzer in accordance with Clinical Laboratory Standards Institute (CLSI) recommendations. Methods The analytical performance of an ACE open-channel assay (BÜHLMANN Laboratories AG) on the cobas® c 503 analyzer was evaluated. Assay parameters were established based on Roche recommendations for adapting cobas® c 502 – where ACE was previously being tested on – open channel parameters to the c503 analyzer.Validation included precision, correlation, linearity, and interference from hemolysis, icterus, and lipemia (HIL), using a total allowable error of 10%. The data were visualized using Microsoft Excel and analyzed following CLSI recommendations. Results Total imprecision of the assay was <6% across both manufacturer-provided quality control materials. Correlation with patient samples (n = 40) against the c502 ACE assay was excellent (R² = 0.974) over a concentration range of 10 – 157 U/L. The assay demonstrated excellent linearity across the analytical measurement range (4 – 140 U/L). Finally, the ACE assay exhibited tolerance to hemolysis, icterus, and lipemia up to Roche cobas serum indices thresholds of 50, 5, and 100, respectively. Conclusion Using a conversion system to transfer assay parameters from the cobas® c502 to the c503 analyzer, we established an ACE assay that exhibited excellent analytical performance in terms of precision, method comparison, linearity, and tolerance to HIL interferences.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.018 | 0.016 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.004 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".